The guppies in both tanks are all losing their color. It's fading on there tails. They swimming & acting just fine though. NONE of the other fish are losing their color. In fact, there colors are vibrant and there fins are all intact and beautiful. I have 4 Lyretail Mollies & there fins are really long and thick & SUPER colorful. My Angel has long fins & his black & silver is super bright. My shrimp are even starting to develop red on their bodies & when I bought them they were clear.

I don't understand why the guppies are losing there color. I got 3 guppies from petsmart and the rest from petco. All of the other fish came from Petsmart.
Per Petco, they only use aquarium salt in the molly tanks & no others.

Food: Every other day I feed Aqueon Color Enhancing Flakes & once a week frozen bloodworms.

Any ideas????? At first I suspected fin rot, but NONE of the other fish exhibit any signs of the guppies problems.